1. Field of the Invention
The present invention relates to a dry toner for use in electrophotographic systems and to a method of producing this toner.
2. Description of the Related Art
The applications of the image-forming methods in dry toner electrophotographic systems have become quite diverse in recent years as speed and image quality have increased and are no longer limited to use in office applications. An example of these applications is the print-on-demand (POD) field, while use in packaging applications, e.g., packaging printing, is also under investigation. Packaging printing requires a high durability in order to prevent the image from being destroyed even when the printed image undergoes bending, and investigations have been carried out in order to obtain a high printed image durability.
Japanese Patent Application Laid-open Nos. 2003-255601 and 2006-11437 introduce art that provides a substantial improvement in the bending resistance; this is achieved by incorporating a UV-curable material in the toner and carrying out exposure to UV after fixing. However, one problem here is that an image forming apparatus capable of carrying out UV irradiation has a complex structure and as a consequence is expensive. In addition, the UV cure becomes inadequate when the printing speed is raised and this also makes raising the printing speed problematic.
In Japanese Patent Application Laid-open No. 2011-65155, the attempt is made to increase the flexibility by reducing the particle diameter of the toner in order to reduce the thickness of the recording film; however, it is difficult just by reducing the recording film thickness to obtain a bending resistance sufficiently high to enable use in packaging printing applications.
Japanese Patent Application Laid-open Nos. H10-73959, 2009-122171, 2005-292362, H6-175389, and 2005-275336 disclose the addition of a thermoplastic elastomer to toner in order to inhibit fissuring of the toner in the developing device and in order to provide an excellent hot offset. However, due to the use of thermoplastic elastomer having a high softening point, the low-temperature fixability is impaired and a balance between the low-temperature fixability and the bending resistance of the output product is not achieved.